## 1.20. Scripting

Scripting languages and scripting applications differ from compiled languages and applications in that the application is interpreted as run rather than compiled into a machine-understandable format. You can use shell scripting for many of your scripting needs, but there are times when you'll want to use something more sophisticated. Though not directly a part of a Unix system, most Unix installations come with the tools you need for this more complex scripting -- Perl (Chapter 41), Python (Chapter 42), and Tcl.

These three scripting languages seem so prevelant within the Unix world that I think of them as the Unix Scripting language triumvirate.

Perl is probably the granddaddy of scripting. Created by Larry Wall, this language is probably used more than any other for creating complex scripts to perform sophisticated functionality with Unix and other operating systems. The language is particularly noted for its ability to handle regular expressions, as well as working with files and other forms of I/O.

Python isn't as widespread as Perl, but its popularity is growing. One reason it's gaining popularity is that as a language, Python is more structured and a little more verbose than Perl, and therefore a little easier to read. In addition, according to its fans, Python has more object-oriented and data-manipulation features than the file-manipulation and regular-expression manipulation of Perl.

Tcl is particularly prevelant within Linux systems, though it's use is widespread throughout all Unix systems. It's popular because it's simpler to learn than Perl and allows scripters to get up to speed more quickly than you can with Perl or Python. In addition, the language also has access to a very popular graphical user interface library called the Tk toolkit. You'll rarely hear about Tcl without the associated Tk.

--TOR and SP

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